Conventionally, in automobiles, home electronics appliances, etc., signal lines and power lines are used in which an electric wire having a core wire made of a copper material is connected to a terminal also made of a copper material. On the other hand, in the automobile industry, in consideration of influences on the environment, it is an important issue to increase the fuel efficiency by making vehicles lighter. For this reason, attention is now paid to electric wires in which aluminum which is lighter in weight than copper is used as a material of a core wire. However, aluminum is prone to electrolytic corrosion under the presence of water and copper ions. That is, there is a problem that if water enters a connection portion of an aluminum core wire and a copper terminal, the water turns into electrolytic liquid between the members made of the different metals and aluminum electrolytic corrosion is prone to occur because of a difference between the corrosion potentials of aluminum and copper. In view of this, a terminal-attached electric wire has been proposed that prevents occurrence of electric corrosion by covering a connection portion of an aluminum core wire and a copper terminal with resin (refer to Patent document 1, for example).
In the terminal-attached electric wire disclosed in Patent document 1, a terminal is crimped onto a conductor portion that is exposed by removing an insulation covering at an end portion of a covered wire. This terminal-attached electric wire is set in a molding die consisting of, for example, upper and lower dies and resin is injected into a cavity formed in the molding die. As a result, the conductor-exposed portion is covered with the resin at the connection portion of the conductor and the terminal. A resin portion is formed as a result of solidification of the resin.